Get the most out of pregnancy diagnostics

by Gabe Middleton, DVM

I can still remember some of my college professors say that a “pregnancy check” on a cow is really an “open check” so that she can be inseminated again as quickly and efficiently as possible. I agree with that statement, but there may be a bit more information that can be given to a producer rather than just “pregnant” or “open.”

There is no doubt that finding open cows likely represents the highest value in timely pregnancy diagnostics. When a cow is determined to be open, she needs to either be enrolled in a resynchronization program so that she can be re-inseminated. The cost of additional days open is expensive for the dairy. Most estimates would value an additional day open at $3-4/cow/day. Additional days at the end of lactation tend to be much less profitable, particularly in mature cows.

Methods of pregnancy diagnosis should be carefully considered. Rectal ultrasound is probably the most common method of diagnosing pregnancy at the moment. The advantages are many. Obtaining real time results helps to enroll cows in the re-insemination protocol and likely helps improve compliance within that protocol. Ultrasound can also accurately aid veterinarians in twin diagnosis. Twin diagnosis is helpful insomuch as the cows are recorded and managed as carrying twins. When abortion occurs, it is helpful to know if a cow was pregnant with twins because presence of pathogens causing abortion is much less likely. Also, early calving prior to due date is much more likely with twins and is part of the reason why these cows experience increased incidence of transition cow disease. More time in the close-up pen may help mitigate transition cow disease. Early dry off (10-14 days earlier) is an effective way to help use information to reduce disease.

Many dairies do a recheck of pregnancy status at around 60 days. An experienced practitioner can also find the gender of the fetus accurately and quickly at this time. This may be unnecessary in some situations; however, dairy producers have found it helpful to determine the gender of the fetus so they can more accurately match the newborn calf to the cow if several cows freshened simultaneously. This is probably more important on dairies that don’t have dedicated maternity staff to immediately process every newborn calf.

Scanning ovaries of cows that are enrolled for pregnancy check or for some other reason is always a valuable tool. Evaluating the cyclic activity of cows gives tremendous insight as to the nutrition and potential transition cow disease status of the herd. For example, if cystic ovaries begin to appear on certain groups of cows, the vet can communicate with the nutritionist. It benefits the dairy if there is a collaborative effort to communicate and use the information that ovarian structures can provide.

There are other methods of pregnancy diagnosis other than ultrasound. Milk and blood pregnancy tests are readily available. These tests are accurate and can determine pregnancy status as early as an ultrasound. On many herd software systems, the results are automatically uploaded as soon as the lab reports them. This typically only takes a day or two. This system may fit the management style of some dairies, but not others. The major challenge with many milk and blood pregnancy tests is that the results are not real time. This means that the cow has to be found again for an intervention if she is open. These tests also only give you a “pregnant” or “open” answer and don’t give any insight in regards to twins or impending pregnancy loss. In other words, ultrasound may identify a fetus that is dying, where the alternative tests will likely still find her to be pregnant. Again, alternative pregnancy testing can work on some herds. Make sure you examine the advantages and disadvantages. Do a thorough cost analysis. What appears to be cheaper doesn’t always provide the most value.

The advent of activity monitoring systems has changed the reproductive program on many dairies. These systems accurately and effectively find cows in estrus. It is unrealistic to think that they eliminate the need to perform a pregnancy check on a cow. The initial pregnancy confirmation needs to occur. Due to the variable expression of estrus of cows, particularly high producing cows, there still needs to be an accurate diagnosis of pregnancy early on. These systems do provide an excellent means to identify cows that have pregnancy loss after that initial confirmation of pregnancy. The systems can eliminate the need to do rechecks on pregnant cows as the system will identify activity on cows that lose their pregnancy. There are some false positives, however, so these cows will need a confirmation that they did indeed lose the calf.

Evaluate the method of pregnancy diagnostics on your farm. Don’t just look at the cost of the test; rather, examine the value it provides and how it fits into the general management of your farm. Remember that excellent reproduction is necessary to have consistent, high production.